The evolution of the stimulus control of constricting behaviour: inferences from North American gartersnakes (Thamnophis)

No metrics data to plot.

The attempt to load metrics for this article has failed.

The attempt to plot a graph for these metrics has failed.

The full text of this article is not currently available.

Brill’s MyBook program is exclusively available on
BrillOnline Books and Journals. Students and scholars affiliated with an
institution that has purchased a Brill E-Book on the BrillOnline platform
automatically have access to the MyBook option for the title(s) acquired by the
Library. Brill MyBook is a print-on-demand paperback copy which is sold at a
favorably uniform low price.

Behavioural traits that have evolved relatively recently can provide unique insights into the nature of early evolutionary stages and the adaptive significance of such traits. We used this “recent origins” approach by examining the stimulus control of constricting behaviour in Western Terrestrial Gartersnakes (Thamnophis elegans), a species in which constriction evolved within the last several million years. Using mice and frogs as prey, we tested the hypothesis that prey struggling is a key stimulus eliciting constriction. Mean prey struggling intensity was significantly higher for mice than for frogs, and the snakes often constricted mice but rarely constricted frogs. Furthermore, for each prey type separately, the likelihood of constriction increased with increased prey struggling, while relative prey size was held constant. The context-dependent nature of constriction in T. elegans supports the notion that, as these snakes began feeding substantially on rodents, constricting behaviour was selected specifically to subdue these vigorously struggling prey. Thus, in this early evolutionary stage, prey struggling appears to be both a proximate cue and a selective factor promoting the spread of constricting behaviour. In some snake species representing more ancient origins of constriction, the behaviour is elicited by pre-strike cues that appear to be correlated with struggling ability. Therefore, if the behaviour of T. elegans is taken as a proxy for an early evolutionary stage of constriction in general, we can infer an evolutionary shift in the stimulus control of the behaviour. Our results suggest a general conceptual model for the sequence of evolutionary changes in the stimulus control of behaviour in which the critical cue changes from the actual object/event for which a response is beneficial to some feature correlated with that object/event.